Scanning devices for analyzing liquid samples delivered thereto and sorting particles such as biological cells contained therein according to sensed characteristics thereof are known as shown, for example, in U.S. Pat. No. 3,826,364, Bonner et al, which patent is assigned to the assignee of the present invention. Flow cell sorters of this type are designed to provide a large number of cells of a given subpopulation. Other cell sorting systems, such as shown in U.S. Pat. Nos. 3,924,947 and 4,009,435, and in an article entitled Individual Cell Sorting by Stovel and Sweet, The Journal of Histochemistry, Vol. 27, No. 1 pp. 284-288, 1979, move a collecting surface or tray beneath a charged droplet sorter so that deflected droplets are laid down sequentially in a scanning pattern. Often, prior art devices of this type require complicated, and expensive, moving means for accurately moving the surface or tray onto which the individual cells are sorted, and elaborate control circuitry for the control thereof. Also, the broad idea for operating a particle sorter to deposit a single particle into a manually positionable multiwell tray to collect individual particles in the tray wells is contained in an article entitled Antigen-Specific Identification and Cloning of Hybridomas with Fluorescence-activated Cell Sorter (FACS) by D. R. Parks, V. M. Bryan, V. T. Oi and L. A. Herzenberg, Proc. Natl. Acad. Sci. USA, Vol. 76, No. 4, pp. 1962-1966, April 1979, Genetics.